Home About us Contact
|
Home About us Contact | ||
|
|
||
Evolutionary Questions (evolutionary + question)
Selected AbstractsEcological limits and diversification rate: alternative paradigms to explain the variation in species richness among clades and regionsECOLOGY LETTERS, Issue 8 2009Daniel L. Rabosky Abstract Diversification rate is one of the most important metrics in macroecological and macroevolutionary studies. Here I demonstrate that diversification analyses can be misleading when researchers assume that diversity increases unbounded through time, as is typical in molecular phylogenetic studies. If clade diversity is regulated by ecological factors, then species richness may be independent of clade age and it may not be possible to infer the rate at which diversity arose. This has substantial consequences for the interpretation of many studies that have contrasted rates of diversification among clades and regions. Often, it is possible to estimate the total diversification experienced by a clade but not diversification rate itself. I show that the evidence for ecological limits on diversity in higher taxa is widespread. Finally, I explore the implications of ecological limits for a variety of ecological and evolutionary questions that involve inferences about speciation and extinction rates from phylogenetic data. [source] Predicting the past distribution of species climatic nichesGLOBAL ECOLOGY, Issue 5 2009David Nogués-Bravo ABSTRACT Predicting past distributions of species climatic niches, hindcasting, by using climate envelope models (CEMs) is emerging as an exciting research area. CEMs are used to examine veiled evolutionary questions about extinctions, locations of past refugia and migration pathways, or to propose hypotheses concerning the past population structure of species in phylogeographical studies. CEMs are sensitive to theoretical assumptions, to model classes and to projections in non-analogous climates, among other issues. Studies hindcasting the climatic niches of species often make reference to these limitations. However, to obtain strong scientific inferences, we must not only be aware of these potential limitations but we must also overcome them. Here, I review the literature on hindcasting CEMs. I discuss the theoretical assumptions behind niche modelling, i.e. the stability of climatic niches through time and the equilibrium of species with climate. I also summarize a set of ,recommended practices' to improve hindcasting. The studies reviewed: (1) rarely test the theoretical assumptions behind niche modelling such as the stability of species climatic niches through time and the equilibrium of species with climate; (2) they only use one model class (72% of the studies) and one palaeoclimatic reconstruction (62.5%) to calibrate their models; (3) they do not check for the occurrence of non-analogous climates (97%); and (4) they do not use independent data to validate the models (72%). Ignoring the theoretical assumptions behind niche modelling and using inadequate methods for hindcasting CEMs may well entail a cascade of errors and naïve ecological and evolutionary inferences. We should also push integrative research lines linking macroecology, physiology, population biology, palaeontology, evolutionary biology and CEMs for a better understanding of niche dynamics across space and time. [source] Bayesian approaches in evolutionary quantitative geneticsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 4 2008R. B. O'HARA Abstract The study of evolutionary quantitative genetics has been advanced by the use of methods developed in animal and plant breeding. These methods have proved to be very useful, but they have some shortcomings when used in the study of wild populations and evolutionary questions. Problems arise from the small size of data sets typical of evolutionary studies, and the additional complexity of the questions asked by evolutionary biologists. Here, we advocate the use of Bayesian methods to overcome these and related problems. Bayesian methods naturally allow errors in parameter estimates to propagate through a model and can also be written as a graphical model, giving them an inherent flexibility. As packages for fitting Bayesian animal models are developed, we expect the application of Bayesian methods to evolutionary quantitative genetics to grow, particularly as genomic information becomes more and more associated with environmental data. [source] 20 Questions on Adaptive DynamicsJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 5 2005D. WAXMAN Abstract Adaptive Dynamics is an approach to studying evolutionary change when fitness is density or frequency dependent. Modern papers identifying themselves as using this approach first appeared in the 1990s, and have greatly increased up to the present. However, because of the rather technical nature of many of the papers, the approach is not widely known or understood by evolutionary biologists. In this review we aim to remedy this situation by outlining the methodology and then examining its strengths and weaknesses. We carry this out by posing and answering 20 key questions on Adaptive Dynamics. We conclude that Adaptive Dynamics provides a set of useful approximations for studying various evolutionary questions. However, as with any approximate method, conclusions based on Adaptive Dynamics are valid only under some restrictions that we discuss. [source] Using Bayesian inference to understand the allocation of resources between sexual and asexual reproductionJOURNAL OF THE ROYAL STATISTICAL SOCIETY: SERIES C (APPLIED STATISTICS), Issue 2 2009C. Jessica E. Metcalf Summary., We address the problem of Markov chain Monte Carlo analysis of a complex ecological system by using a Bayesian inferential approach. We describe a complete likelihood framework for the life history of the wavyleaf thistle, including missing information and density dependence. We indicate how, to make inference on life history transitions involving both missing information and density dependence, the stochastic models underlying each component can be combined with each other and with priors to obtain expressions that can be directly sampled. This innovation and the principles described could be extended to other species featuring such missing stage information, with potential for improving inference relating to a range of ecological or evolutionary questions. [source] Advances in insectivore and rodent systematics due to geometric morphometricsMAMMAL REVIEW, Issue 2 2009LENKA BAR ABSTRACT 1Morphometrics, the study of the variation and change in form amongst organisms, serves as a basic methodological tool in various fields of biological research, including systematics. Because it includes information about spatial relationships amongst anatomical landmarks, geometric morphometrics is more suitable for analyzing morphometric variation than methods based on distance measurements. 2Geometric morphometrics allows us to answer general ecological and evolutionary questions about shape. 3In this paper, landmark-based methods are described and illustrated, based on a dataset of measurements from 295 Apodemus mandibles, and the applications of such methods in the systematics of insectivores (Eulipotyphla) and rodents (Rodentia) are summarized. [source] Genomic tools and cDNA derived markers for butterfliesMOLECULAR ECOLOGY, Issue 9 2005ALEXIE PAPANICOLAOU Abstract The Lepidoptera have long been used as examples in the study of evolution, but some questions remain difficult to resolve due to a lack of molecular genetic data. However, as technology improves, genomic tools are becoming increasingly available to tackle unanswered evolutionary questions. Here we have used expressed sequence tags (ESTs) to develop genetic markers for two Müllerian mimic species, Heliconius melpomene and Heliconius erato. In total 1363 ESTs were generated, representing 330 gene objects in H. melpomene and 431 in H. erato. User-friendly bioinformatic tools were used to construct a nonredundant database of these putative genes (available at http://www.heliconius.org), and annotate them with blast similarity searches, InterPro matches and Gene Ontology terms. This database will be continually updated with EST sequences for the Papilionideae as they become publicly available, providing a tool for gene finding in the butterflies. Alignments of the Heliconius sequences with putative homologues derived from Bombyx mori or other public data sets were used to identify conserved PCR priming sites, and develop 55 markers that can be amplified from genomic DNA in both H. erato and H. melpomene. These markers will be used for comparative linkage mapping in Heliconius and will have applications in other phylogenetic and genomic studies in the Lepidoptera. [source] Molecular ecology of social behaviour: analyses of breeding systems and genetic structureMOLECULAR ECOLOGY, Issue 2 2001Kenneth G. Ross Abstract Molecular genetic studies of group kin composition and local genetic structure in social organisms are becoming increasingly common. A conceptual and mathematical framework that links attributes of the breeding system to group composition and genetic structure is presented here, and recent empirical studies are reviewed in the context of this framework. Breeding system properties, including the number of breeders in a social group, their genetic relatedness, and skew in their parentage, determine group composition and the distribution of genetic variation within and between social units. This group genetic structure in turn influences the opportunities for conflict and cooperation to evolve within groups and for selection to occur among groups or clusters of groups. Thus, molecular studies of social groups provide the starting point for analyses of the selective forces involved in social evolution, as well as for analyses of other fundamental evolutionary problems related to sex allocation, reproductive skew, life history evolution, and the nature of selection in hierarchically structured populations. The framework presented here provides a standard system for interpreting and integrating genetic and natural history data from social organisms for application to a broad range of evolutionary questions. [source] Breastfeeding structure as a test of parental investment theory in Papua New Guinea,AMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 5 2009David P. Tracer Evolutionary parental investment theory predicts that parents invest preferentially in offspring best able to translate investments into fitness payoffs. It has also been proposed that where the reproductive prospects of offspring are directly correlated with parental investment and variance in fertility is higher for males than females, parents in better condition should bias investment toward males while those in poorer condition should bias investment toward females. Lactation is arguably among the costliest forms of investment expended by mothers and is thus expected to be allocated in ways consistent with fitness payoffs. Quantitative data collected among 110 Papua New Guinean mother-infant pairs during 470 h of focal follows on nursing frequency and duration and responses to infant demands by maternal and offspring characteristics are presented to provide empirically-based descriptions of infant care and tests of evolutionary parental investment theory. Results indicate that mothers show very high levels of investment in offspring. However, although breastfeeding in developing countries is often characterized as on-demand, fussing and crying by infants were only attended to with breastfeeding about 30% of the time. Contrary to expectations of parental investment theory that parents should invest less in poorer quality offspring, mothers increased investment in offspring in poorer condition. The expectation that mothers in better condition would bias investment toward male offspring was also not supported; better nourished mothers biased investment toward female offspring. This study illustrates how infant feeding data may be used for testing larger evolutionary questions such as those derived from parental investment theory. Am. J. Hum. Biol. 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||||||||